Any discussion of documents, devices, acts or knowledge in this specification is included to explain the context of the invention. It should not to be taken as an admission that any of the material forms a part of the prior art base or the common general knowledge in the relevant art in Australia or elsewhere on or before the priority date of the disclosure herein.
Sufferers of asthma or chronic obstructive pulmonary disease (COPD) often use a metered dose inhaler in order to inhale a bronchodilatory drug such as Salbutimol into their lungs, thereby opening up their pathologically constricted airways. However, if the patient is unable to co-ordinate spraying of the medication into their mouth (which is actuated by depressing a medication canister inside a housing of the inhaler), with a deep inspiratory breath, much of the medication may be deposited on the back of their mouth instead of being drawn deep into their lungs. A spacer may be particularly beneficial for patients struggling with this timing issue as the spacer allows the patient draw medication deep into the lungs by a process of spraying the medication into the spacer and then slowly and deeply breathing in and out, usually for about 5 to 10 breaths.
Whilst not being an admission of common general knowledge, U.S. Pat. No. 5,816,240 describes a spacer having: a chamber with a mouthpiece; an inspiratory valve with a radially extending disc and an axially extending plug retainer, the inspiratory valve being configured for opening on inspiration by a patient and closing upon expiration by a patient; and an expiratory valve comprising a radially extending ring, the inspiratory valve being configured for opening upon expiration by a patient and dosing upon inspiration by a patient.
A disadvantage of prior art spacers such as the one mentioned above may be the use of two valves which both move during inspiration and expiration, potentially causing increased resistance to flow and leading to overly complex designs. Another disadvantage with these types of spacers may be the need for ultrasonic welding of the chamber components, potentially adding to the complexity and reducing efficiency of assembly during manufacture.
Thus, it may be advantageous to provide a new spacer, or new component for a spacer, which reduces, limits, overcomes, or ameliorates some of the problems, drawbacks, or disadvantages associated with prior art devices, or provides an effective alternative to such devices.